Deep fryers, such as turkey fryers, are widely used in the United States. They often include a 20-to-30 quart vessel for holding the cooking oil and the food item to be fried, as well as a heat source, such as a propane heater or an electric heater, to heat the cooking oil to a desired temperature. The vessel is typically supported by a stand or a base into which the heat source is usually incorporated. While some deep fryers use electrical heaters, most deep fryers used to cook turkeys in the United States use propane or natural gas burners to heat the cooking oil. A turkey holder is inserted into the cavity of the turkey to be fried is inserted into a basket or placed on a rack. A handle is attached to the turkey holder such that the turkey can be manually lowered into the hot cooking oil. Once the turkey is cooked, the user removes the turkey by grasping the handle attached to the turkey holder and lifting the holder and turkey from the hot oil.
Deep fryers, while pervasive, can be dangerous to the user. Multiple fires and burns are caused annually by their use because of the defects present in many existing designs. For example, commonly used deep fryers have metal cooking vessels with metal handles. The vessels and handles become very hot during use and may cause serious burns to anyone coming in contact with their surfaces. Another significant disadvantage of existing deep fryers is the relatively tall and relatively narrow burner bases frequently used. The tall and narrow base design has a relatively high-center of gravity, making them prone to tipping over, thereby splashing or spilling hot cooking oil on the heat source or on a user. In the case of propane burners, such splashed cooking oil may be ignited by the propane burner. Because of the quantity of cooking oil (e.g., 30 quarts or more), large fires may quickly ensue.
The open flame design presents other issues. Burners as currently designed allow the flame to spread out and around the sides of the cooking vessel. This is inefficient and requires more fuel to heat the cooking oil to the desired temperature.
Cooking oils can be safely heated to a certain auto-ignition temperature which varies for different oils (e.g., above 400° F.). Heating the oil above its particular auto-ignition temperature causes the oil to spontaneously ignite in the cooking vessel. Existing deep fryers often lack thermostats or other means to ensure that the temperature of the oil is prevented from reaching the auto-ignition temperature, such as by automatically shutting off the burner when the auto-ignition temperature is approached.
By far the most dangerous aspect of using existing deep fryers, however, is encountered when the user stands over the deep fryer in order to manually lower a relatively large and often heavy turkey into the hot cooking oil. Turkeys are frequently purchased frozen and subsequently thawed out, dried, and/or seasoned prior to being fried. In certain cases where the turkey has not been completely thawed, or where moisture or water remains on the turkey or in its cavity, a sudden vigorous boiling and splashing of the hot oil may occur when the turkey is being placed into the deep fryer. As another example, users often overfill the vessel with cooking oil and do not allow sufficient remaining space in the vessel for the oil that is displaced by the turkey when the turkey is lowered into the cooking vessel. Cooking oil also expands when heated, and a surprisingly large volume of oil is displaced by the turkey when the turkey is inserted into the hot oil. Both the heat expansion of the oil and the volume of oil displaced by the turkey frequently result in hot oil overflowing or spilling out of the cooking vessel when the turkey is lowered into the oil.
The sudden splashing or spilling of hot oil may cause the user to drop the turkey into the deep fryer, rather than lowering it into the vessel in a controlled manner, thus further increasing the splashing and boiling over of the hot oil, or even tipping the fryer over. Lowering the turkey into the cooking oil is so dangerous that many turkey fryers are accompanied by express instructions to turn off the burner during this step. Unfortunately, these instructions are often either ignored or not read by users. The existing lack of features to prevent this potential splashing and spilling over of hot oil results in multiple user burns and injuries, and in significant property damage and fires annually.
Finally, existing turkey fryers may have relatively short gas-supply conduits connecting them to a fuel gas source, such as a pressurized container. Because of its proximity, the fuel gas source may easily be splashed or otherwise come into contact with ignited cooking oil, further increasing the danger to users.